Telephone-exchange system.



C. W. KECKLER. TELEPHONE EXCHANGE SYSTEM. mmcmou FILED NOV. 5. 1911.

1,302,808. Patented May 6, 1919.

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UNITED STATES PATENT @FETCE.

CHARLES W. KECKLER, OF NEWARK, NEW JERSEY, ASSIGNOR T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

l TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented May 6, 1919.

Application filed November 5, 1917. Serial No. 200,344.

Newark, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in TelephonaExchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to systems in which a called station is signaled by the automatic application to the called line of an intermittent signaling current.

It is the practice in systems of this character to signal the called party by intermittently actuating the signal at the desired station. This result is usually accomplished by supplying the signaling current to the line through a commutator or other means, whereby the application of the current is interrupted at predetermined intervals for certain periods, "causing corresponding silent or inactive periods of the station signal. It frequently happens that the connection of the link circuit to the Wanted line occurs during one of the interrupted or silent periods so that the signal at the called station is not actuated until the completion of that period, thus causing a delay in signaling the called party. p

The obj ect. of the invention is to provide a simple and inexpensive circuit arrangement whereby the usual periodically interrupted signaling current is impressed upon the called line immediately upon connecting a link circuit therewith.

In accordance with one feature of this in vention the signaling current is supplied intermittently to the link circuit through a plurality of common interrupters cooperating so that current may be obtained from one of the interrupters at any time. Belays are included in each link circuit cooperating with another set of common interruptcrs operating in synchronism with the signaling current interrupters, upon the connection of the link circuit with the called line, to select the particular signaling interrupter capable of immediately transmitting the signaling current to the line.

These and other features not specifically mentioned above will more clearly appear from the fEOllOWlIlg specification and the an nexed drawing, a figure of which diagram matlcally represents the calling extremity of an ordlnary cord c1rcu1t embodying the invention.

As shown inthe drawing, A represents an ordinary line circuit provided with'the usual apparatus, including an ordinary calling signal and a cut-off relay 12, and terminating in jack 11. B represents the calling extremity, terminating in a plug 10, of a cord circuit of a well-known type, in which the battery for talking purposes is supplied through a repeating coil and in which the usual supervisory signal 14 is controlled by the ordinary supervisory relay 16. Ringing relay 15 is controlled by relay 18, in cooperation with relay 13 and marginal tripping relay 17.

For the purpose of clearness, that portion of the circuit arrangement which may be common to several cord circuits is shown below the line (3-6. A constantly rotating shaft 9 carries signaling in'terrupters or commutators 1, 2 and 3, a segment of each of which obtains signaling current through the disk 4:, also mounted on shaft 9. Carried by the same shaft and rotating in synchronism-with commutators 1, 2 and 3, respectively, are battery supply commutators 5, 6 and 7, asegment of each of which is served with battery current through a disk 8, also mounted on shaft 9. The brushes for the various commutators are so adjusted that a brushwill be in contact with the live segments of each of the commutators 1, 2 and 3, throughout the periods during which the brushes are in contact with the live segments of the correspondingcommutators 5, 6 and '7, respectively. Selecting relays 23, 24 and 25 in each cord circuit determine the particular one of commutators 1, 2 and 3 to be used in a given case, and are themselves controlled by the cooperation of relay 13 and battery supply commutators 5, 6 and 7.

It is thought that the invention may be more readily understood from a description of the operation of the system and it will be so described.

Assuming that connection with line A is desired, the operator will insert plug 10 in jack 11, whereupon a circuit will be completed from battery through supervisory signal. 14;, relay l3, sleeves plug 10 and jack 11, and relay 12 to ground. In the usual manner, cutofi' relay 12 will operate and signal14 will be displayed; relay 13 will also operate, and by the closure of its upper alternate contact will establish the continuity of the tip strand of the cord circuit. The closure of contact 19 of relay l3, establishes a circuit proceeding from battery through ringing relay 15, normal contact of relay 18, normal contact of relay 17, and contact 19 of relay 13, to ground. Relay 15 thereupon operates and through the closure of its alternate contacts prepares connections forsupplying the signaling current tothe tip and ring strands of the cord.

Let it be further assumed that the various commutators 1, 2, 3, 5, 6 and 7 are in and winding of relay 25, and contact 22 of relay 13, to ground. Relay 25 will thereupon operate and be retained in an operated position by means of a circuit from battery, contact 35 (which contact is adapted to close before contact 34 opens), relay 25, and contact 22 of relay 13, to ground. Signaling current will now be applied to the line A and the calling signal thereof will be operated in the usual manner with alternating actuated and silent periods by such current flowing from its source, disk 4, live segment of commutator 3 and its associated brush in contact therewith, upper alternate contact of relay '25, relay 17 and lower alternate contactof relay 15, ring strand of the cord circuit, rings of plug 10 and jack 11, signal of line A, tips of Jack 11 and plug 10; upper alternate contact of relay 13, tip strand of the cord circuit, and upper alternate contact of relay 15, to ground.

In accordance with well-known principles of operation, relay 17 will remain unoperated until the called party responds to the signal by removing the receiver from its hook and thereby rendering the signal ineffective, whereupon the current flowing through relay 17 will be suflicient to cause its operation. By the opening of its alternate contact, relay 17 removes the short circuit around relay 18, whereupon relay 18 is actuated over a circuit proceeding from battery through relay 15, relay 18, and contact 19 of relay 13 to ground. Through the closure of its alternate contact, relay 18 provides a self-locking circuit extending from battery, alternate contact, and Winding of relay 18, and contact 19 of relay 13 to ground, whereupon relay 18 is retained in an operated position. Relay 15 is also released, due to the closure of the alternate contact of relay 18, and the elimination of the short circuit for- 1,3o2,sos

merly existing around relay 18. The signaling current is removed from the tip and ring strands of the cord circuit by the opening of the alternate contacts of relay 15 and the continuity of each strand for talking purposes is reestablished by the closure of the respective normal contact of relay 15.

In the ordinary manner supervisory relay 16 will operate over a circuit from battery through a portion of the repeating coil, relav 16, lower normal contact of relay 15, ring strand of the cord circuit, rings of plug 10 and jack '11, station equipment of line A, tips of jack 11 and plug 10, upper alternate contact of relay 13, upper normal contact of relay 15, and through another portion of the repeating coil to ground. In operating, relay 16 in the usual manner through the closure of its alternate contact, shunts supervisory signal 14 by resistance 38 and thereby retires the signal 14.

It will be noted that relay 25 in operating opens normal contacts 36 and 37, thereby preventing the operation of relays 23 and 24, when the brushes of their respective battery commutators 5 and 6 are in contact with the live segments thereof.

Upon the completion of the conversation the subscriber on line A replaces the receiver, whereupon, in the usual manner, relay 16 releases, removing the resistance 38 from its shunt relation with signal 14 and that signal is again displayed by means of its former circuit. The operator, observing the disconnect signal, removes plug 10 from the jack 11, whereupon all apparatus returns to normal.

In case the brush of battery commutator 6 had been in contact with a live portion of such commutator when plug 10 was inserted in jack 1]., relay 24 would have been operated over a circuit from battery, disk 8, live segment of commutator 6, and the brush in contact therewith, contact 29 of relay 23, contact 36 of relay 25, contact 30 and Winding of relay 24, contact 21 of relay 13 to ground. Thereupon relay 24 would be locked in an operated position by virtue of a circuit from battery, alternate contact 31 (which contact is adapted to close before contact 30 opens), and winding of relay 24, contact 21 of relay 13 to ground. By the closure of its upper alternate contact, relay 24 would prepare a circuit whereby signaling current would be supplied to relay 17 from the source, disk 4, live segment of commutator 2 and the associated brush which at that time would be in contact there with, and upper alternate contact of relay 24, to relay 17. In this case the opening of contacts 32 and 33 of relay 24 would prevent the operation of relays 23 and 25 when the live segments of the associated battery commutators 5 and 7, respectively, were in contact with their associated brushes. The

remainder of the operation of the system would be the same as that previously described.

In a similar manner, in case the live segment of battery commutator 5 had been in contact with its associated brush when plug 10 was inserted in jack 11, relay 23 would have been operated over a circuit from battery, disk 8, live segment of commutator 5 and the associated brush in contact therewith; contact 37 of relay 25, contact 32 of relay 24,. contact 26 and winding of relay 23, and contact 20 of relay 13 to ground. Relay 23 would thereupon be locked in its operated position by means of a circuit from battery, contact 27 of relay 23 (which contact is adapted to close before contact 26' opens), and contact 20 of relay 13 to ground. By the closure of its upper alternate contact, relay 28 would prepare a circuit whereby signaling current would be supplied from the source, disk 4, live segment of commutator 1 and its associated brush, which at that time would be in contact therewith, upper alternate contact of relay 23 to relay 17 In this case the opening of contacts 29 and 28 would prevent the operation of relays 24: and 25, respectively, when the live segments of the associated battery commutators 6 and 7, respectively, made contact with their associated brushes. The remainder of the operation of the system would agree with that previously described.

It will be readily observed from the above description that the usual signaling current is automatically applied to the line immediately upon connecting the link circuit therewith, thereby promoting a prompt re sponse by the called party with a consequent earlier termination of the conversation and a reduction in the length of the period during which the link circuit is required for the particular connection.

It will also be evident that the drain upon the source of signaling current will be distributed throughout a complete cycle since some one of the interrupters is available for service at any time.

What is claimed is:

1. In a telephone exchange svstem, a line provided with a signal and terminating at a central oflice, a link circuit at said central oflice adapted for connection with said line circuit, a source of signaling current, a plurality of circuit interrupters associated with said source each adapted to transmit current from said source for predetermined periods at stated intervals, said interrupters adapted to operate in immedlate se' quence to constantly provide one of said interrupters available for transmission of current from said source, and means, operating upon the connection of said link circuit with said line circuit, for connecting said available one of said interrupters to said link circuit to impress signaling current from said source upon said connected line to cause the intermittent operation of said signal.

2. In a telephone exchange system, a line circuit, a link circuit adapted for connection therewith, a source of signaling current, a plurality of circuit interrupters connected with said source each adapted to interrupt its connection therewith for certain periods at certain intervals, said interrupters operating in immediate sequence to render one of said interrupters effective for transmission of current from said source at any time, and means operating upon the connection of said link circuit with said line circuit to associate with said link circuit said one of said interrupters effective at the time of said connection to transmit periodically interrupted signaling current from said source to said line.

3. In a telephone exchange system, a line circuit terminating at a central office, a link circuit at said central oiiice adapted toconnect with said line, a source of signaling current for signaling on said line, a plurality of interrupters associated with said source, each adapted to supply signaling current for predetermined periods at stated intervals, said interrupters cooperatively related to supply current from said source at any time through one of said interrupters, and means included in each of said link circuits for selectively associating one of said interrupters with said link circuit upon the connection of said link circuit with said line circuit to immediately transmit said signaling current to said line.

4:. In a telephone exchange system, a line circuit, a link circuit for connection therewith, a source of signaling current adapted to be associated with said link circuit for signaling on said line, a set of circuit interrupters operating in continuous sequence each adapted to be connected with said link circuit to supply signaling current from said source for predetermined periods at certain intervals, and means operating upon the con nection of said link circuit with said line circuit for selectively connecting to said link circuit one of aid interrupters to immediately supply current from said source to said line for the remainder of said predetermined period coincident with the connection of said link circuit and said line circuit and thereafter to supply said signaling current at said certain intervals for said predetermined periods.

5. In a signaling system for producing signals for predetermined periods at stated intervals, a source of signaling current, means for producing said signals at any time and thereafter to reproduce said signals at said stated intervals, said means comprising a plurality of constantly operating switching means included with said source each adapted to provide periodically interrupted signaling current from said source, and means for automatically selecting one of said switching means capable of immediately providing said current at said time.

6. In a signaling system, a signal adapted to be actuated for predetermined periods at stated intervals, a source of signaling current adapted to so actuate said signal and means to actuate said signal at any time for a time no longer than said predetermined period and thereafter to actuate said signal for said predetermined periods at said stated intervals, said means comprising a plurality of switching means each adapted to transmit said signaling current from said source, said switching means cooperating to constantly provide one of said switching means available for transmission of said current, and means for selectively associating with said signal Said one of said switching means transmitting current at said time.

7. In a telephone exchange system, a line circuit and a calling signal thereon, link circuit for connection therewith, a plurality of sources of periodically interrupted signaling current, such interruptions occuring during different parts of a cycle to continuously provide signaling current from one of said sources, and means operating upon the connection of said link circuit with said line circuit to associate with said link circuit said one of said sources providing current coincidently with said connection to immediately actuate said signal for a period not exceeding the usual period between said interruptions and thereafter to periodically interrupt such actuation.

8. In a telephone exchange system, a line circuit provided with a signal, a link circuit for connection therewith, a plurality of sources of periodically interrupted signaling current with interrupted periods so timed as to render continuously available one of said sources, and means operatin upon the connection of said link circuit w1th said line circuit to associate with said link circuit said one of said sources available at the time of said connection to immediately actuate said signal.

9. In a telephone exchange system, a line provided with a signal, a link circuit for connection therewith, a plurality of sources of periodically interrupted signaling current with interruptions timed to insure at any time the exclusive availability of one of said sources for providing signaling current, and means operating upon the connection of said link circuit with said line circuit to associate with said link circuit said source available at the time of said connection for immediately actuating said signal.

10. In a telephone exchange system, a line circuit provided with a signal adapted for periodic operation, a link circuit for COI1110- tion therewith, a source of signaling current, a plurality of interrupters associated with said source, each adapted to transmit periodically interrupted current therefrom, said interrupters causing interruptions so timed as to render one of said interrupters exclusively available for transmitting current from said source at any time, and means operating upon the connection of said link circuit with said line circuit to selectively associate with said link circuit said one of said interruptens available for transmitting current at the time of said connection to cause the immediate operation of said signal followed by alternate silent and operating periods thereof.

11. In a telephone exchange system, a line circuit, a link circuit for connection therewith, a source of signaling current, a plurality of circuit interrupters associated with said source, each adapted to transmit current from said source for predetermined periods at stated intervals, said interrupters adapted to operate in immediate succession to constantly provide one of said interrupters exclusively available for transmitting current from said source, and means operating upon the connection of said link circuit with said line circuit for selectively and exclusively associating with said link circuit said interrupter available for transmitting signaling current at the time of said connection for immediately transmitting signaling current from said source to said line circuit.

12. In a telephone exchange system, a link circuit for connection therewith, a source of signaling current, a plurality of circuit interrupters associated with said source, each adapted to transmit current from said source for predetermined periods at stated intervals and cooperating with the remainder of said interrupters to render one of said interrupters continuously available for transmitting current from said source, means operating upon the connection of said link circuit with said line circuit for selectively associating with said link circuit said interrupter having a transmitting period coincident with said connection, for immediately transmitting signaling current to said line for the remainder of said transmitting period and thereafter for said predetermined periods at said stated intervals, and means controlled by said selective means for excluding the remainder of said interrupters from association with saidlink circuit during the continuance of said connection.

13. In a telephone exchange system, a line circuit, a link circuit for connection therewith, a source of current for signaling purposes, a second source of current, a constantly rotating shaft, a set of signaling interrupters mounted upon said shaft and connected to said source of signaling current,

each of said interrupters adapted to transmit signaling current for predetermined periods at stated intervals and cooperating with the remainder of said interrupters to constantly provide one of said interrupters exclusively available at any time for transmitting said current, a set of a similar number of interrupters mounted upon ,said shaft and connected to said second source of current, each of said interrupters adapted to transmit interrupted current from said second source in synchronism with the corresponding one of said signaling interrupters, means operating upon the connection of said link circuit with said line cir-' cuit and cooperating with the corresponding one of said second set of interrupters to selectively associate with said link circuit said signaling interrupter available for transmitting signaling current at the time of said connection to immediately impress said signaling current upon said line, and means rendering said remaining interrnpters of both of said sets inefiiective relative to said link circuit during the continuance of said connection.

14:. In a telephone exchange system, a line circuit, a link circuit for connection therewith, a source of signaling current, a plurality of current conductors, means for connecting said conductors with said source in seriatim to form complete cycles, a common current conductor, means operating upon the connection of said link with said line to connect said common conductor with one of said plurality of conductors connected to said source at the instant of said connection of said link with said line, and means also operating at said instant to connect said common conductor with said link to transmit signaling current from said source to said line.

In witness whereof, I hereunto subscribe my name this 1st day of November A. D.,

CHARLES W. KE GKLER.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. 0. 

